This invention relates generally to test fixtures and methods of evaluating gaskets, O-rings, and other sealing devices and, more particularly, relates to a static test fixture and method of evaluating gasket leakage under accelerated, simulated, service conditions for the purpose of predicting service life.
Gaskets are used in a variety of industrial and consumer products to provide seals between mating assemblies. Examples of such products include internal combustion engines, piston-type compressors, and steam turbines. Depending upon the application, gaskets are subjected to a wide range of temperatures and pressures in which these conditions, along with the chemical nature of the pressurizing medium (such as air, water, steam, refrigerant, etc.), are significant factors in selecting the appropriate material from which to construct the gasket. In order to facilitate the decision associated with selecting the appropriate gasket material for the desired application, gasket test assemblies are utilized to measure specific mechanical properties of gasket samples which information is useful in aiding the selection of the correct gasket for the particular application.
Typical gasket test assemblies used to test the sealing characteristics of gaskets are of two varieties. The first gasket test assembly comprises a static test fixture which is used to check gasket performance under static conditions where neither surface in contact with the gasket is allowed to move. The second gasket test assembly comprises a dynamic test fixture which is used to check gasket performance under dynamic conditions where at least one of the surfaces in contact with the gasket is allowed to move with respect to the gasket during operation. These typical test assemblies are useful in measuring the mechanical properties of the tested gaskets which in turn allows gasket behavior to be quantified to a certain measured degree. While the test results gathered from these assemblies provide insight as to the mechanical properties of the gaskets subjected to the testing procedure, the assemblies and corresponding test results have the disadvantage of not being generally useful for predicting the service life of the tested gasket.
It is therefore an object of the present invention to provide an apparatus and method for testing gasket specimens under simulated service conditions whereby the service life of the gasket may be predicted.
It is a further object of the present invention to provide an apparatus and method whereby the cycles of temperature and pressure which occur in service may be accelerated for reducing the time required in evaluating gasket candidates.